Distinguishing between cannabis-induced psychotic disorder and psychotic disorder with concurrent cannabis use: a diagnostic challenge

Abstract

Approximately one-third of patients presenting with a first episode of psychosis have a history of cannabis use. Some of these patients meet the criteria for cannabis-induced psychotic disorder (CIPD), which is regarded as a disorder with better outcomes compared to other psychotic disorders. The aim of this paper was to determine whether there are differences in clinical and demographic features between patients with CIPD and patients with a first episode of primary psychotic disorder (PPD) with concurrent cannabis use (CU). A literature search in the PubMed database for papers published in English was conducted. A total of 12 studies published between 2002 and 2019 were selected. Available data support the hypothesis that CIPD is a distinct clinical entity from PPD with CU. Differences were found in clinical presentation, as patients with CIPD tend to have a lower intensity of overall psychotic symptoms, greater insight into psychosis, a higher likelihood of visual hallucinations, depersonalization, and derealization, as well as more intense manic symptoms and hostility than patients with PPD with CU. In terms of family history, patients with CIPD are more likely to have a close relative with a substance use disorder but less likely to have a close relative diagnosed with a psychotic disorder. However, a significant percentage (25-45%) of patients initially treated for CIPD will meet criteria for a chronic psychotic disorder in the following years, and continuous cannabis use is associated with poor prognosis, independent of the initial diagnosis. In these conditions, early intervention is crucial, and substance use treatment should be considered a priority for cannabis users who develop psychotic symptoms.